Draft control device for oil burners



March 6, 1945 J. E. THORNQUIST 2,370,391

DRAFT CONTROL DEVICE FOR OIL BURNERS Filed May 25, 1941 Jawi INVENTOR BYW ATTORNEY v the furnace.

Patented Mar. 6, 1945 UNITED STATES PATENT OFFICE My invention relatesto a draft control for oil burners, wherein it is desired to provide ameans of cutting off the flow of air to an oil burner when the same isnot in operation.

In the use of oil burners it is common practice -to provide a fan orother means for providing a forced draft for the furnace at the time theoil burner is in operation. This forced draft of air is provided tosupport combustion and to permit all of the oil to be burned. The fan isordinaril connected to an air inlet which is open at all times. When theoil burner is not in operation the natural draft in the chimney causesa. constant flow of air through the furnace. This flow of cold air intothe furnace cools the furnace much more quickly than would otherwise bethe case. The air flowing through the furnace merely rises up throughthe chimney and is wasted.

It is the object of my invention to provide a means of cutting on theflow of air to the oil burner when the oil burner is not in operation.Thus during the time the oil burner is not throwing a flame into thefurnace the air is kept from entering the lower portion of the furnace.Thus there is not a constant flow of cold air through the furnace,enabling the furnace to keep warm for a longer period of time.

It is an object of the present invention to provide a check valve orbutterfly valve which is so devised as to open when the oil burner fanis in operation, but which will clos when the fan is not in operation.Thus as soon as the oil burner and the fan creating a draft thereforstarts into operation, the valve opens to admit air. However, as soon asthe fan ceases operation, the valve closes and the air suppl to thefurnace is cut off.

It is a feature of the present invention to provide a draft of air whichis warmer than that usually supplied to the oil burner. I prefer to takethe air from a point substantially spaced from the floor and preferablynear the door of As a certain amount of heated air escapes from thefurnace and as the fair surrounding th furnace is at a slightly highertemperature than air at a greater distance from the furnace, the airwhich is drawninto the furnace by the fan is warmer than would otherwisebe the case. Providing warm air for the operation of the oil burner isadvantageous as less heat is required to heat the air, and accordinglymore heat may be used to actually heat the furnace.

Ill

intake opening of the air. Thus, if too much air is being supplied tothe furnace my valve may be set so that less air would enter. throughthe same. By this means 1 provide a draft regulating device inconjunction with the draft closing device so that one apparatus willserve two purposes.

It is a feature of my invention that my valve for controlling the draftto the oil burner may be either in the form of a balanced butterflyvalve, which is open by a reduction in air pressure on one sideof thesame, or may be opened by a check valve. In either instance gravityprovides the valve actuating mechanism.

A further feature of my invention resides in the fact that my valve maybe regulatedto vary the It is a further feature of my invention that mydraft control may be simply manufactured and may be constructed to fitvirtually any oil burner on the market. This adapting means is necessaryto equip each construction of oil burner to my draft control device, butonce this has been done a considerable saving in fuel costs will benoted.

These and other objects and novel features of my invention will be moreclearly and fullyset forth in the following specification and claims.

In the drawing forming a part of my specifica-. tion: i

Figure 1 is a side elevation view of an oil burner in position before afurnace, and my draft control device attached thereto.

Figure 2 is an elevation view of the draft control device showing theconstruction thereof.

Figure 3 is a sectional view through the draft control device, theposition of the section being indicated by the line 3-3 of Figure 2.

Figure 4 is a cross sectional view through the draft control device ofFigure 2, the position of the section being indicated by the line 4.4 ofFigure 2.

Figure 5 is a diagrammatic view of a modified form of valveconstruction.

Figure 6 is a bottom plan view of the valve construction illustrated inFigure 5.

Figure 7 is a cross sectional view through, the valve of Figures 5 and6, the position of the section being indicated by the line 1-1 of Figure6.

The furnace A may be of any desirable type and is shown having a loweropening l0, an inspection door II, and a clean out door I 2. The openingI0 provides an ash pit opening when the furnace A is used to burn coal.In. the present instance, however, where an oil burner is used theopening I0 is closed by a closure plate II, having an openingtherethrough in communication with an air and fuel duct l4.

and inexpensively" Various types of burners are constructed in diiierentmanners so that the burner construction illustrated is merelydiagrammatic. The burner B is supported from a base 15 on the floor USby means of standards l1. An oil supply line i9 delivers oil to theburner which may be provided with a suitable float device 20. The airinlet duct 2| is provided with a suitable fan or blower, as illustrated,which forces air through the duct l4 and into th lower portion'of thefurnace A when the burner is in operation. Normally the end of the inletduct 2| is open to admit air into the duct at all times. In the presentinstance, however, the inlet duct is closed by means of a hollow ductclosure 22 which is con-' nected by the tapered conduit 23' totheconduit 24. An elbow 25 supports the pipe or conduit 26, which supportsthe small and of a reducer 21. A hollow cylindrical casing 29 isprovided for the valve C, which is best illustrated in Figures 2, 3, and4 of the drawing. It will be noted that the valve C is of the butterflytype and is positioned adjacent the front of the furnace A to collectrelatively warm air.

As best illustrated in Figures 2, 3, and 4 of the drawing, a flat ring30 is provided with a cylin drical sleeve portion 3| of a size to fitwithin the cylindrical casing 29. An end flange 32 extends over the endof the casing 29 to hold the ring 30 in proper position. The ring 30provides an aperture of a size slightly reduced with respect to the sizeof the casing 29, and this aperture is normally closed by the butterflyvalve 33.

The butterfly valve 33 is substantially circular. in shape and the edgethereof tapers downwardly and inwardly at the top 34 and also at thebottom 35. This tapered edge limits the pivotal movement of thebutterfly valve 33 on its pivots 36.

A bracket 31 is secured to the butterfly valve 33 on one side of thevertical center thereof, and above the horizontal center. The bracket3'1 is secured to the valve 33 by bolts 39, or other suitable means. Thebracket 31 supports a pivot 36 which projects outwardly beyond thebracket and which engages between the body of the'ring 30 and a strip 40cut from the body of the ring and bent outwardly.

A bracket 4| is secured to the valve 33 in oppositely disposed relationto the bracket 31 and is fastened in place by any suitable means, suchas the bolts 42. A pivot 36 is supported by the bracket 4| and extendsoutwardly beyond the bracket to engage between the body of the ring 36and a strip 43 cut from the ring 30. The pivots 36 supported by thebrackets 31 and 4| are aligned and permit the valve to pivot withrespect to the ring 30.

The bracket 4| is similar to the bracket 31 with the exception that itis longer than the bracket 31 to accommodate the adjusting bolt 44. Theadjustirg bolt 44 is provided with an operating end 45 bent at rightangles to the body of the bolt 44 by means of which the bolt may berotated.

Secured to the rear surface of the ring 30 by any suitable means, suchas the bolts or rivets 46, I provide a bracket 41 which includes an arm49 extending rearwardly from the ring, and provided with an end 50 whichis bent at right angles from the arm 49 to extend inwardly toward thecenter of the housing 29. This arm 49 and end 50 are so devised as toprovide a stop for the butterfly valve 33. Thus as the butterfly valve33 swings inwardly, as disclosed by the dotted outline in Figure 4 ofthe drawing, the stop bolt 44 will strike the end 50 of the arm 49 tolimit pivotal movement. In this manner the opening of the butterflyvalve 33 may be regulated.

Near the top of the valve 33 I provide a threaded stud 5|, which extendsinwardly from the valve and which is secured thereto by nuts 52. Aweight 53 is threaded on the stud 5| and this weight is adjustablysupported so as to vary the differential pressure necessary to swing thebutterfly valve 33 into open position.

Inoperation, when the fan of the oil burner B starts into operation areduction in pressure is experienced within the fan inlet which issecured to the housing 29. Accordingly the atmospheric pressuresurrounding this compartment acts to swing thebutterfly valve 33 intothe position illustrated in. dotted outline in Figure 4 of the drawing.As long as the fan of the oil burner continues in operation thebutterfly valve 33 will remain in the inclined position shown in dottedoutline inFigure 4 to permit air to enter the oil burner-,

As soon-as the fan of the burner stops its rotation the butterfly'valve33 swings closed, stopping the flow of air into,thefurnace and thuspreventing thecooling of the interior of the furnace by adraft of coolair passing therethrough.

In Figures 5, 6, and '1 of the drawing a modified form of constructionis illustrated. In this form of construction the air'inlet pipe to theoil'burncr is indicated, in general by the numeral 54. This airinletpipe has circumferential openings therein, which are covered by theenclosing casing 55.

' illustrated in Figures 6 and '1 Thecasing 55 1s, preferably formed intwo parts, splitl'at-56, so that the housing may be readily clamped overthe inlet openings in the pipe 54. The interior of the hollow casing 55is connected to the hollow pipe or conduit 51,which are connected by theelbows 59 and 60 to the small end ofa-reducer 6|. A valve casing 62,which is hollow and cylindrical, is secured to the large end of thereducer 6|.

The valve provided in the housing 62 is best of the drawing. A ring 63is provided with a cylindrical flange 64 thereupon, which terminates inan edge flange 65. A bridg strip 66 is secured by suitable means, suchas the bolts or rivets 61, to the lower surface of the ring 63. Acentral bearing 69 is provided on the bridge strip 66, and a sleeve 10is. secured by any suitable means, such as the head screw 1|, to thebearing 69. The upper extremity of the sleeve 10 terminates in acircular flange or disc 12, which is provided with apertures 13therethrough. I

Within the sleeve", I provide a rod 14 which is longitudinally slidablewithin the sleeve 10. A collar 15 lsprovided near the lower extremity ofthe rod 14 to limit slidable movement of the rod in an upward direction.A shoulder 16 is provided on the rod 14 near the upper end thereof. andthe disc-shaped end 11 of a cylinder 19 is clamped between the shoulder16 and a nut 8|] on the rod 14. The cylinder 19 therefore moves with therod 14.

A ring-shaped valve disc 8| is secured to the flange 82 of the cylinder19. The valve disc 8| has an opening therethrough, which is ofapproximately the same size as the diameter of the cylinder 19. Theflange 12 in the cylinder 19 and a valve plate 83 loosely encircling therod 14 above the flange 12 acts to close the opening 13 when the valvedisc 8| and cylinder 19 is in elevated position and tends to close.

In operation, when the oil burner fan starts into acts as a pistonwith-- operation a reduction in pressure is experienced within thehousing 82 so that the atmospheric pressure surrounding this housingraises the valve disc 8|. The cylinder I9 raises with the valve disc 8|andln this upward movement of the valve disc 8| the valve plate 83raises slightly to permit air to flow readily through the apertures 13'in the flange I2.- Thus the valve disc 8| may raise without diflicultyand air may enter the oil burner. When the oil burner fan ceasesoperation the suction acting upon the valve disc 8| decreases and theweight of the disc 8| tends to close the same. Air has been draftedwithin the cylinder 19 between the closed end 11 thereof, and the flange12. The tendency for the valve disc 8| to lower tends to compress theair within the cylinder I9, thus pressing the valve plate 88 against theflange 12. Accordingly the lowering of the valve disc 8| is retarded andthe valve disc 8| drops gradually, thus providing suflicient air to pprt combustion until the fan is entirely stopped.

In the use of my valve for closing the draft to oil burners I have foundthat a considerable percentage of fuel may be saved through the use ofthis device. I have found that because of the cutting off of the streamof cool air flowing through the furnace when the oil burner is not inuse longer periods of time elapse between successive operations of theoil burner, resulting in a considerable saving in fuel.

In accordance with the patent statutes, I have described the principlesof construction and operation of my draft control device for oilburners, and while I have endeavored to set forth the best embodimentsthereof, I desire to have it understood that these are only illustrativeof a means of carrying out my invention, and that obvious changes may bemade within the scope of the following claims without departing from thespirit of my invention.

I claim:

1. A draft control for a furnace having an inspection door at a pointspaced from the bottom thereof, an oil burner casing extending into thefurnace near the bottom thereof, and a draft creating fan forming a partof said oil burner, an inlet to said fan including an upwardly extendingconduit extending substantially vertically from said draft creating fan,an elbow on said upwardly extending conduit, a horizontally extendingconduit extending toward the inspection door of the furnace, a. housingsecured to the end of said horizontally extending conduit, said housinghaving an open side therein, a butterfly valve mounted in said openside, said butterfly valve being movably mounted to open when suction iscreated by said fan and to close said open ide when said fan is not inoperation.

2. A draft control for a furnace having an inspection door at a pointspaced from the bottom thereof, an oil burner casing extending into thefurnace near the bottom thereof, a draft creating fan forming a part ofsaid oil burner to force air through said casing, an inlet to said fanextending upwardly therefrom, a tubular conduit extending upwardly fromsaid inlet, an elbow secured to the top of said tubular conduit, ahorizontally extending tubular conduit extending laterally from saidelbow, said laterally extending tubular conduit extending toward theinspection door of the furnace, a second elbow at the end of saidlaterally extending tubular conduit, a valve housing secured to saidelbow, said valve housing having an open end therein, said valve meanmounted in said open end, said valve means operable to open when saidfan is in operation and to close when said fan is not in operation.

JONAS E. THORNQUIST.

